grunty
I have reached Yuki nirvana
Don't make it sound like there's a rule. :p There are shows with no OP or ED on the first ep, and there are shows which only have the ED.The recent years, the OP plays as ED on ep 1 and on 2nd ep, they play the ED. (exception is Madoka)
So far the plot is quite dumb, and cliched. Its basically evil monsters and good guys (/swords) arriving from the future and fighting over history. The lines are very usual as well. The music is good since this is basically a very similar setting as Bokumatsu Kikansetsu Irohanihoheto which was also by Fukasawa. OP is Okay.